CA2108073C - Single transformer switching regulator - Google Patents
Single transformer switching regulatorInfo
- Publication number
- CA2108073C CA2108073C CA002108073A CA2108073A CA2108073C CA 2108073 C CA2108073 C CA 2108073C CA 002108073 A CA002108073 A CA 002108073A CA 2108073 A CA2108073 A CA 2108073A CA 2108073 C CA2108073 C CA 2108073C
- Authority
- CA
- Canada
- Prior art keywords
- direct
- current energy
- secondary winding
- battery
- high frequency
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M3/00—Conversion of dc power input into dc power output
- H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
- H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
- H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
- H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
- H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
- H02M3/33569—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements
- H02M3/33576—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements having at least one active switching element at the secondary side of an isolation transformer
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
- H02J7/02—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries for charging batteries from ac mains by converters
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M3/00—Conversion of dc power input into dc power output
- H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
- H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
- H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
- H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
- H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
- H02M3/33507—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of the output voltage or current, e.g. flyback converters
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J2207/00—Indexing scheme relating to details of circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
- H02J2207/20—Charging or discharging characterised by the power electronics converter
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Dc-Dc Converters (AREA)
- Charge And Discharge Circuits For Batteries Or The Like (AREA)
- Stand-By Power Supply Arrangements (AREA)
Abstract
A switching regulator comprises a single transformer having a primary winding connected in an input circuit for receiving direct-current energy and a secondary winding connected in an output circuit, and a switching transistor connected in series with the primary winding. A high frequency pulse generator triggers the switching transistor so that it interrupts the direct-current energy at a high frequency. A rectifier is provided for converting high frequency energy developed in the secondary winding into direct-current output energy, which is maintained constant by controlling the high frequency pulse generator. A low voltage detector produces a signal when the direct-current energy in the input circuit falls below a specified value. in response to the signal from the low voltage detector, constant direct-current energy is derived from a battery and applied to the output circuit as backup power.
Description
TITLE OF THE INVENTION
"Single Transformer Switching Regulator"
BACKGROUND OF THE INVENTION
Field of the Invention The present invention relates generally to switching regulators, and more particularly, to a switching regulatGr having a power backup unit.
Description of the Related Art A prior art switching regulator having power backup unit comprises a first DC-DC converter for converting an input direct-current voltage to a desired level, and a second power backup DC-DC converter for converting a direct-current voltage from a battery to the desired level. A first diode is provided for coupling the first output terminal of the first DC-DC converter to the first input terminal of the second converter, the second output terminal of the first converter being connected direct to the second input terminal of the second converter. The battery is connected through a second diode to the first input of the second converter. The output of the first converter is regulated at a level higher than the battery voltage so that under normal conditicns no current is supplied from the battery to the second converter. If the output of the first converter reduces below the battery voltage, a current is supplied from the battery to the second converter via the second diode to produce a desired direct-current output voltage from the second converter, instead of from the first converter.
- la -Since the efficiency of the prior art switching regulator during normal operation is represented by the multiplied efficiencies of the first and second converters, and since each of the converters comprises a transformer, the efficiency value is low and thus necessitated a design consideration that minimizes the power dissipation of individual components, while ensuring their safety margins.
Additionally, because of the use of two transformers, the pricr art switching regulator is costly, bulky, and adds extra weight to the regulator.
_ NE-545 21 08073 SUMMARY OF THE INVENTION
"Single Transformer Switching Regulator"
BACKGROUND OF THE INVENTION
Field of the Invention The present invention relates generally to switching regulators, and more particularly, to a switching regulatGr having a power backup unit.
Description of the Related Art A prior art switching regulator having power backup unit comprises a first DC-DC converter for converting an input direct-current voltage to a desired level, and a second power backup DC-DC converter for converting a direct-current voltage from a battery to the desired level. A first diode is provided for coupling the first output terminal of the first DC-DC converter to the first input terminal of the second converter, the second output terminal of the first converter being connected direct to the second input terminal of the second converter. The battery is connected through a second diode to the first input of the second converter. The output of the first converter is regulated at a level higher than the battery voltage so that under normal conditicns no current is supplied from the battery to the second converter. If the output of the first converter reduces below the battery voltage, a current is supplied from the battery to the second converter via the second diode to produce a desired direct-current output voltage from the second converter, instead of from the first converter.
- la -Since the efficiency of the prior art switching regulator during normal operation is represented by the multiplied efficiencies of the first and second converters, and since each of the converters comprises a transformer, the efficiency value is low and thus necessitated a design consideration that minimizes the power dissipation of individual components, while ensuring their safety margins.
Additionally, because of the use of two transformers, the pricr art switching regulator is costly, bulky, and adds extra weight to the regulator.
_ NE-545 21 08073 SUMMARY OF THE INVENTION
2 It is therefore an object of the present invention to provide a
3 switching regulator which is efficient, light-weight and low cost.
4 According to the present invention, there is provided a switching regulator having an input circuit and an output circuit. The switching 6 regulator comprises a single transformer having a primary winding 7 connected in the input circuit for receiving direct-current energy and a 8 secondary winding connected in the output circuit, and a switching element 9 connected in series with the primary winding. A monitor circuit is connectedto the output circuit for monitoring the direct-current energy in the output 11 circuit. A high frequency pulse generator, energized by the direct-current 12 energy in the input circuit, generates a high frequency pulse with a duty 13 ratio inversely variable as a function the monitored direct-current energy in 14 the output circuit. The switching element is responsive to the high 15 frequency pulse for interrupting the direct-current energy supplied to the 16 primary winding of the transformer. A rectifier circuit is connected in the 17 output circuit for converting high frequency energy developed in the 18 secondary winding into direct-current energy. A low voltage detector is 19 provided for producing a low voltage indication signal when the direct-current energy in the input circuit falls below a specified value. In response 21 to the low voltage indication signal, constant direct-current energy is derived 22 from a battery and supplied to the output circuit as backup power.
23 According to a first specific aspect of the present invention, the 24 constant direct-current energy is derived by a circuit comprising a second 2s switching element connected in series with the battery across the secondary 26 winding, and a second high frequency pulse generator energized by the 27 direct-current energy in the output circuit for generating a high frequency 28 pulse with a duty ratio inversely variable as a function of the direct-current 29 energy in the output circuit detected by the monitor circuit. In the presence of the low voltage indication signal, the second switching element interrupts a current supplied from the battery in response to the high frequency pulse to generate high frequency energy in the main secondary winding. This high frequency energy is converted to direct-current energy in the output circuit by the rectifier as backup power.
According to a second specific aspect of the present invention, the transformer has an auxiliary secondary winding, and the constant direct-current energy is derived by a circuit comprising a second switching element connected in series with the battery across the main secondary winding, and a second high frequency pulse generator connected to the auxiliary secondary winding for generating a high frequency pulse with a variable duty ratio inversely proportional to the direct-current energy detected by the monitor circuit. In the presence of the low voltage indication signal, the second switching element interrupts a current supplied from the battery in response to the high frequency pulse to generate high frequency energy in the main secondary winding.
Acccrding to a third specific aspect of the present invention, a rechargeable battery is used, and the constant direct-current energy is derived by a circuit comprising a second rectifier connected to the secondary winding of the transformer for converting high frequency energy developed therein to direct-current energy, and a battery charger for receiving the direct-current energy from the second rectifier for charging the rechargeable battery. A voltage stabilizer is connected to the rechargeable battery for producing a - 3a -constant direct-current voltage. In response to the low voltage indication signal, the constant direct-current voltage is applied to the output circuit of the switching regulator as backup power.
In accordance with the present invention, there is provided a switching regulator having an input circuit and an output circuit, comprising: a single transformer having a primary winding connected in said input circuit for receiving direct-current energy and a secondary winding connected in said output circuit; monitor means for monitoring direct-current energy in said output circuit; a switching element connected in series with said primary winding; high frequency pulse generator means energized by the direct-current energy in said input circuit for producing a high frequency pulse and causing said switching element to interrupt said direct-current energy supplied to said primary winding in response to the high frequency pulse, said pulse having a duty ratio inversely variable as a function of the direct-current energy monitcred by said monitor means; rectifier means connected in said output circuit for converting high frequency energy developed in said secondary winding into direct-current energy7 low voltage detector means for producing a low voltage indication signal when said direct-current energy in said input circuit falls below a specified value; a battery; and means connected to said battery for deriving constant direct-current energy from said battery and coupling the constant direct-current energy to said output circuit in response to said low voltage indication signal.
- 3b -In accordance with another aspect of the invention, there is provided a switching regulator having an input circuit for receiving direct-current energy and an output circuit, comprising: a single transformer having a primary winding connected in said input circuit for receiving direct-current energy and a secondary winding connected in said output circuit;
monitor means for monitoring direct-current energy in said cutput circuit; a first switching element connected in said input circuit in series with said primary winding; first high frequency pulse generator means energized by the direct-current energy of said input circuit for producing a first high frequency pulse and causing said first switching element to interrupt said direct-current energy of said input circuit in response to the first high frequency pulse, said first high frequency pulse having a duty ratio inversely variable as a function of the direct-current energy monitored by said monitor means; first rectifier means connected in said output circuit for converting high frequency energy produced in said secondary winding into said direct-current energy of said output circuit;
low voltage detector means for producing a low voltage indicaticn signal when said direct-current energy of said input circuit falls below a specified value; a rechargeable battery;
second rectifier means connected to said secondary winding for converting high frequency energy produced therein to direct-current energy; a battery charge for receiving direct-current energy from the second rectifier means and charging said rechargeable battery; a stabilizer connected to said recharge-able battery for producing a constant direct-current energy;
and means for applying said constant direct-current energy to said output circuit in response to said low voltage indication signal.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will be described in further detail with reference to the accompanying drawings, in which:
Fig. 1 is a circuit diagram, partly in block form, of a switching regulator according to the present invention, in which a constant frequency clock pulse source is used in the output circuit of the switching regulator in 2 the same manner as in its input circuit, 3 Fig. 2 is a circuit diagram of a modification of the switching 4 regulator of Fig. 1, in which a self-oscillating pulse generator is used in the output circuit;
6 Fig. 3 is a circuit diagram of a furtner modification of the switching 7 regulator of Fig. 1, in which a rechargeable battery is used as a backup 8 power source and recharged by the use of an additional secondary 9 winding;
Fig. 4 is a circuit diagram of a modification of the switching 11 regulator of Fig. 3, in which the rechargeable battery is used in combination 12 with the self-oscillating pulse generator of Fig. 2 using an additional 13 secondary winding;
14 Fig. 5 is a circuit diagram of a further modification of the switching 15 regulator of Fig. 3, in which the rechargeable battery is used in combination16 with the clocked pulse width modulation of Fig. 1, using a rectifier connected 17 to the main secondary winding; and 18 Fig. 6 is a circuit diagram of a modification of the embodiment of 19 Fig. 5, in which a single photo-coupler monitors the DC output voltage during normal operating conditions, and a voltage stabilizer supplies 21 constant DC output voltage during power failure.
23 Referring now to the drawings in which corresponding parts are 24 marked with same reference numerals and have identical significances 2s throughout the drawings. As represented in Fig. 1, a switching regulator 26 according to a first embodiment of the present invention generally 27 comprises an input circuit 11 and an output circuit 12 and a single 28 transformer 10 for inductively coupling the input circuit 11 to the output 2 9 circuit 12. The input circuit 11 includes a full-wave rectifier 13 in which the mains AC voltage at input terminals 14, 15 are converted to a DC voltage ~ 1 0&073 which appears across power lines 16 and 17 to which the primary winding 2 10a of transformer 10 is connected in series with a switching transistor 21. A
3 voltage divider is coupled across the power lines 16 and 17 to produce an 4 operating voltage Vcc at a circuit junction 20 between a resistor 18 and a
23 According to a first specific aspect of the present invention, the 24 constant direct-current energy is derived by a circuit comprising a second 2s switching element connected in series with the battery across the secondary 26 winding, and a second high frequency pulse generator energized by the 27 direct-current energy in the output circuit for generating a high frequency 28 pulse with a duty ratio inversely variable as a function of the direct-current 29 energy in the output circuit detected by the monitor circuit. In the presence of the low voltage indication signal, the second switching element interrupts a current supplied from the battery in response to the high frequency pulse to generate high frequency energy in the main secondary winding. This high frequency energy is converted to direct-current energy in the output circuit by the rectifier as backup power.
According to a second specific aspect of the present invention, the transformer has an auxiliary secondary winding, and the constant direct-current energy is derived by a circuit comprising a second switching element connected in series with the battery across the main secondary winding, and a second high frequency pulse generator connected to the auxiliary secondary winding for generating a high frequency pulse with a variable duty ratio inversely proportional to the direct-current energy detected by the monitor circuit. In the presence of the low voltage indication signal, the second switching element interrupts a current supplied from the battery in response to the high frequency pulse to generate high frequency energy in the main secondary winding.
Acccrding to a third specific aspect of the present invention, a rechargeable battery is used, and the constant direct-current energy is derived by a circuit comprising a second rectifier connected to the secondary winding of the transformer for converting high frequency energy developed therein to direct-current energy, and a battery charger for receiving the direct-current energy from the second rectifier for charging the rechargeable battery. A voltage stabilizer is connected to the rechargeable battery for producing a - 3a -constant direct-current voltage. In response to the low voltage indication signal, the constant direct-current voltage is applied to the output circuit of the switching regulator as backup power.
In accordance with the present invention, there is provided a switching regulator having an input circuit and an output circuit, comprising: a single transformer having a primary winding connected in said input circuit for receiving direct-current energy and a secondary winding connected in said output circuit; monitor means for monitoring direct-current energy in said output circuit; a switching element connected in series with said primary winding; high frequency pulse generator means energized by the direct-current energy in said input circuit for producing a high frequency pulse and causing said switching element to interrupt said direct-current energy supplied to said primary winding in response to the high frequency pulse, said pulse having a duty ratio inversely variable as a function of the direct-current energy monitcred by said monitor means; rectifier means connected in said output circuit for converting high frequency energy developed in said secondary winding into direct-current energy7 low voltage detector means for producing a low voltage indication signal when said direct-current energy in said input circuit falls below a specified value; a battery; and means connected to said battery for deriving constant direct-current energy from said battery and coupling the constant direct-current energy to said output circuit in response to said low voltage indication signal.
- 3b -In accordance with another aspect of the invention, there is provided a switching regulator having an input circuit for receiving direct-current energy and an output circuit, comprising: a single transformer having a primary winding connected in said input circuit for receiving direct-current energy and a secondary winding connected in said output circuit;
monitor means for monitoring direct-current energy in said cutput circuit; a first switching element connected in said input circuit in series with said primary winding; first high frequency pulse generator means energized by the direct-current energy of said input circuit for producing a first high frequency pulse and causing said first switching element to interrupt said direct-current energy of said input circuit in response to the first high frequency pulse, said first high frequency pulse having a duty ratio inversely variable as a function of the direct-current energy monitored by said monitor means; first rectifier means connected in said output circuit for converting high frequency energy produced in said secondary winding into said direct-current energy of said output circuit;
low voltage detector means for producing a low voltage indicaticn signal when said direct-current energy of said input circuit falls below a specified value; a rechargeable battery;
second rectifier means connected to said secondary winding for converting high frequency energy produced therein to direct-current energy; a battery charge for receiving direct-current energy from the second rectifier means and charging said rechargeable battery; a stabilizer connected to said recharge-able battery for producing a constant direct-current energy;
and means for applying said constant direct-current energy to said output circuit in response to said low voltage indication signal.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will be described in further detail with reference to the accompanying drawings, in which:
Fig. 1 is a circuit diagram, partly in block form, of a switching regulator according to the present invention, in which a constant frequency clock pulse source is used in the output circuit of the switching regulator in 2 the same manner as in its input circuit, 3 Fig. 2 is a circuit diagram of a modification of the switching 4 regulator of Fig. 1, in which a self-oscillating pulse generator is used in the output circuit;
6 Fig. 3 is a circuit diagram of a furtner modification of the switching 7 regulator of Fig. 1, in which a rechargeable battery is used as a backup 8 power source and recharged by the use of an additional secondary 9 winding;
Fig. 4 is a circuit diagram of a modification of the switching 11 regulator of Fig. 3, in which the rechargeable battery is used in combination 12 with the self-oscillating pulse generator of Fig. 2 using an additional 13 secondary winding;
14 Fig. 5 is a circuit diagram of a further modification of the switching 15 regulator of Fig. 3, in which the rechargeable battery is used in combination16 with the clocked pulse width modulation of Fig. 1, using a rectifier connected 17 to the main secondary winding; and 18 Fig. 6 is a circuit diagram of a modification of the embodiment of 19 Fig. 5, in which a single photo-coupler monitors the DC output voltage during normal operating conditions, and a voltage stabilizer supplies 21 constant DC output voltage during power failure.
23 Referring now to the drawings in which corresponding parts are 24 marked with same reference numerals and have identical significances 2s throughout the drawings. As represented in Fig. 1, a switching regulator 26 according to a first embodiment of the present invention generally 27 comprises an input circuit 11 and an output circuit 12 and a single 28 transformer 10 for inductively coupling the input circuit 11 to the output 2 9 circuit 12. The input circuit 11 includes a full-wave rectifier 13 in which the mains AC voltage at input terminals 14, 15 are converted to a DC voltage ~ 1 0&073 which appears across power lines 16 and 17 to which the primary winding 2 10a of transformer 10 is connected in series with a switching transistor 21. A
3 voltage divider is coupled across the power lines 16 and 17 to produce an 4 operating voltage Vcc at a circuit junction 20 between a resistor 18 and a
5 Zener diode 19. A pulse generator 22, powered by the voltage Vcc as
6 indicated by dotted lines, supplies clock pulses at a frequency, typically 100
7 kHz, to a pulse width modulator 23 in which the width, or duty ratio, of the
8 clock pulse is modulated in accordance with a signal supplied from a photo-
9 coupler 53.
Specifically, the pulse width modulator 23 includes a ramp 11 generator 30 which generates a ramp voltage in response to each clock 12 pulse from the pulse generator 22. A comparator 31 compares the 13 instantaneous value of the ramp voltage with a variable reference voltage 14 developed across a resistor 32 to which the output of the photo-coupler 53 15 is connected. Comparator 31 produces an output signal at one of two 16 values depending on whether it is higher or lower than the reference 17 voltage, so that the output signal of comparator 31 is in the form of a pulse 18 whose duty ratio is inversely proportional to the voltage developed across 19 the resistor 32. Transistors 33 and 34 are connected in series between the 20 circuit junction 20 and power line 17 and their emitter-collector junction is 21 connected to the base of switching transistor 21. The output of comparator 22 31 directly drives the transistor 33 or via an inverter 34 drives the transistor 23 35 to turn on the switching transistor 21 for a duration proportional to the 24 duty ratio of the output pulse of comparator 31. In response, a current 25 pulse is generated in the primary winding 10a, storing magnetic energy 26 therein. During a subsequent turn-off time of switching transistor 21, the 27 energy stored in the primary winding 10a is discharged and transferred to 28 the secondary winding 10b, causing a transient high voltage to develop 2 9 thereacross.
3 0 The input circuit 11 further includes a low voltage detector 24 for ~ 1 08073 .. NE-545 detecting when the input AC voltage is lower than the rated value by means 2 of a comparator 36 which compares a voltage that is developed at a 3 junction between resistors 25 and 26 connected across lines 16, 17 with a 4 rerere.)ce voltage supplied from a battery 37 representing the rated input s voltage of the switching regulator, and generates a low voltage indication 6 signal when Vcc is lower than the reference value.
7 The output circuit 12 includes a battery 40 for the emergency 8 power backup purpose. The positive terminal of battery 40 is connected to 9 the lower end of the secondary winding 10b and the negative terminal
Specifically, the pulse width modulator 23 includes a ramp 11 generator 30 which generates a ramp voltage in response to each clock 12 pulse from the pulse generator 22. A comparator 31 compares the 13 instantaneous value of the ramp voltage with a variable reference voltage 14 developed across a resistor 32 to which the output of the photo-coupler 53 15 is connected. Comparator 31 produces an output signal at one of two 16 values depending on whether it is higher or lower than the reference 17 voltage, so that the output signal of comparator 31 is in the form of a pulse 18 whose duty ratio is inversely proportional to the voltage developed across 19 the resistor 32. Transistors 33 and 34 are connected in series between the 20 circuit junction 20 and power line 17 and their emitter-collector junction is 21 connected to the base of switching transistor 21. The output of comparator 22 31 directly drives the transistor 33 or via an inverter 34 drives the transistor 23 35 to turn on the switching transistor 21 for a duration proportional to the 24 duty ratio of the output pulse of comparator 31. In response, a current 25 pulse is generated in the primary winding 10a, storing magnetic energy 26 therein. During a subsequent turn-off time of switching transistor 21, the 27 energy stored in the primary winding 10a is discharged and transferred to 28 the secondary winding 10b, causing a transient high voltage to develop 2 9 thereacross.
3 0 The input circuit 11 further includes a low voltage detector 24 for ~ 1 08073 .. NE-545 detecting when the input AC voltage is lower than the rated value by means 2 of a comparator 36 which compares a voltage that is developed at a 3 junction between resistors 25 and 26 connected across lines 16, 17 with a 4 rerere.)ce voltage supplied from a battery 37 representing the rated input s voltage of the switching regulator, and generates a low voltage indication 6 signal when Vcc is lower than the reference value.
7 The output circuit 12 includes a battery 40 for the emergency 8 power backup purpose. The positive terminal of battery 40 is connected to 9 the lower end of the secondary winding 10b and the negative terminal
10 thereof connected through a switching transistor 41 to the upper end of the
11 secondary winding 10b so that when the switching transistor 41 is turned on
12 a current is supplied from the battery 40 to the secondary winding 1Ob. A
13 normally closed switch 42 is in shunt with the base and emitter of the
14 switching transistor 41. Switch 42 opens its contact in response to the low
15 voltage indication signal from detector 24. Transistor 41 is thus usually
16 disabled when the input AC voltage is equal to or higher than the rate
17 value. A rectifier 43 is connected to the secondary winding 1 Ob of
18 transformer 10 to produce a DC output voltage across power lines 44 and
19 45 which lead to output terminals 46 and 47, respectively.
Across the power lines 44, 45 is connected a voltage divider to 21 produce a DC operating voltage Vcc at a circuit junction SO between a 22 resistor 48 and a Zener diode 49 connected between line 45 and the 23 negative terminal of battery 40. In a manner similar to the input circuit 11, a 24 pulse generator 51 and a pulse width modulator 52 are provided in the output circuit 12, both of which are powered by the voltage Vcc at junction 2 6 50. Similar to the pulse width modulator 23, the pulse width modulator 52 27 modulates the width of the pulse from pulse generator 51 in accordance 28 with the output of a photo-coupler 54 and applies its output to the base of 29 switching transistor 41.
In order to supply a control voltage to the pulse width modulators NE-545 ~ I ()80~3 23 and 52, the light emitting diodes 53a, 54a of photo-couplers 53, 54 are 2 connected in series across the output terminals 46, 47 with a resistor 55 and3 a shunt regulator 56 which is biased with a reference voltage developed at 4 a junction between resistors 57 and 58. The phototransistor 53b of photo-coupler 53 has its collector coupled to the circuit junction 20 and its emitter 6 to the resistor 32 of pulse width modulator 23. The phototransistor 54b of 7 photo-coupler 54 has its collector coupled to the circuit junction 50 and its8 emitter to the pulse width modulator 52.
g The shunt regulator 56 controls the amount of current supplied to 10 the light-emitting diodes 53a and 54a in response to a voltage variation that11 occurs in the DC output voltage across the output terminals 46, 47, and the 12 impedances of photo-transistors 53b and 54b are caused to vary with such 13 variation, and in proportion to which there is a corresponding variation in 14 the voltage developed across the resistor 32.
When the mains AC voltage is equal to or higher than the rated 16 value, the low voltage detector 24 produces no output, the switch 42 17 remains closed and the switching transistor 41 is not allowed to respond to 18 the output of pulse width modulator 52. Under this normal condition, the 19 DC input from rectifier 13 is chopped by switching transistor 21 at the frequency of the pulse generator 22 and converted to high frequency 21 energy. This high frequency energy is transferred by transformer 10 from 22 the input circuit 11 to the output circuit 12 and converted to DC energy by 2 3 rectifier 43 for delivery to the output terminals 46, 47. In response to the24 fee~b~ck signal from photo-coupler 53, the pulse width modulator 23 produces a pulse whose duty ratio varies inversely as a function of a 2 6 variation in the DC output voltage across terminals 46 and 47 so that the DC27 output voltage is kept constant. This DC voltage is divided by resistor 48 28 and Zener diode 49 to produce the operating voltage for energizing the 29 pulse generator 51 and pulse width modulator 52 in preparation for a 30 possible power failure.
L i ~J 80 1 3 _ NE-545 If the input AC voltage reduces below the rated value, the low 2 voltage detector 24 generates a low voltage indication signal to open the 3 circuit of switch 42 and the switching transistor 41 is now allowed to 4 respond to the output of the pulse width modulator 52. When the s switching transistor 41 is turned on, a current pulse is supplied from the 6 battery 40 to the secondary winding 10b and when it is subsequently 7 turned off a voltage is developed in the secondary winding 10b by counter-8 electromotive force, and the process is repeated as long as the switch 42 is 9 open to generate high frequency energy in the secondary winding 10b.
10 This high frequency energy is converted to DC voltage by the rectifier 43 11 for delivery to the output terminals 46, 47 as in the case of normal 12 operations. In response to the feedback signal from photo-coupler 54, the 13 pulse width modulator 52 produces a pulse whose duty ratio varies 14 inversely as a function of the DC output voltage across terminals 46 and 47 15 to keep it constant as in the case of normal operation. During this abnormal 16 condition, the pulse generator 51 and pulse width modulator 52 are 17 powered by the rechargeable battery 71.
18 A modified embodiment of the present invention is shown in Fig. 2.
19 This modification differs from the previous embodiment in that the
Across the power lines 44, 45 is connected a voltage divider to 21 produce a DC operating voltage Vcc at a circuit junction SO between a 22 resistor 48 and a Zener diode 49 connected between line 45 and the 23 negative terminal of battery 40. In a manner similar to the input circuit 11, a 24 pulse generator 51 and a pulse width modulator 52 are provided in the output circuit 12, both of which are powered by the voltage Vcc at junction 2 6 50. Similar to the pulse width modulator 23, the pulse width modulator 52 27 modulates the width of the pulse from pulse generator 51 in accordance 28 with the output of a photo-coupler 54 and applies its output to the base of 29 switching transistor 41.
In order to supply a control voltage to the pulse width modulators NE-545 ~ I ()80~3 23 and 52, the light emitting diodes 53a, 54a of photo-couplers 53, 54 are 2 connected in series across the output terminals 46, 47 with a resistor 55 and3 a shunt regulator 56 which is biased with a reference voltage developed at 4 a junction between resistors 57 and 58. The phototransistor 53b of photo-coupler 53 has its collector coupled to the circuit junction 20 and its emitter 6 to the resistor 32 of pulse width modulator 23. The phototransistor 54b of 7 photo-coupler 54 has its collector coupled to the circuit junction 50 and its8 emitter to the pulse width modulator 52.
g The shunt regulator 56 controls the amount of current supplied to 10 the light-emitting diodes 53a and 54a in response to a voltage variation that11 occurs in the DC output voltage across the output terminals 46, 47, and the 12 impedances of photo-transistors 53b and 54b are caused to vary with such 13 variation, and in proportion to which there is a corresponding variation in 14 the voltage developed across the resistor 32.
When the mains AC voltage is equal to or higher than the rated 16 value, the low voltage detector 24 produces no output, the switch 42 17 remains closed and the switching transistor 41 is not allowed to respond to 18 the output of pulse width modulator 52. Under this normal condition, the 19 DC input from rectifier 13 is chopped by switching transistor 21 at the frequency of the pulse generator 22 and converted to high frequency 21 energy. This high frequency energy is transferred by transformer 10 from 22 the input circuit 11 to the output circuit 12 and converted to DC energy by 2 3 rectifier 43 for delivery to the output terminals 46, 47. In response to the24 fee~b~ck signal from photo-coupler 53, the pulse width modulator 23 produces a pulse whose duty ratio varies inversely as a function of a 2 6 variation in the DC output voltage across terminals 46 and 47 so that the DC27 output voltage is kept constant. This DC voltage is divided by resistor 48 28 and Zener diode 49 to produce the operating voltage for energizing the 29 pulse generator 51 and pulse width modulator 52 in preparation for a 30 possible power failure.
L i ~J 80 1 3 _ NE-545 If the input AC voltage reduces below the rated value, the low 2 voltage detector 24 generates a low voltage indication signal to open the 3 circuit of switch 42 and the switching transistor 41 is now allowed to 4 respond to the output of the pulse width modulator 52. When the s switching transistor 41 is turned on, a current pulse is supplied from the 6 battery 40 to the secondary winding 10b and when it is subsequently 7 turned off a voltage is developed in the secondary winding 10b by counter-8 electromotive force, and the process is repeated as long as the switch 42 is 9 open to generate high frequency energy in the secondary winding 10b.
10 This high frequency energy is converted to DC voltage by the rectifier 43 11 for delivery to the output terminals 46, 47 as in the case of normal 12 operations. In response to the feedback signal from photo-coupler 54, the 13 pulse width modulator 52 produces a pulse whose duty ratio varies 14 inversely as a function of the DC output voltage across terminals 46 and 47 15 to keep it constant as in the case of normal operation. During this abnormal 16 condition, the pulse generator 51 and pulse width modulator 52 are 17 powered by the rechargeable battery 71.
18 A modified embodiment of the present invention is shown in Fig. 2.
19 This modification differs from the previous embodiment in that the
20 transformer 10 has an auxiliary (feedback) secondary winding 10c having
21 the upper end thereof connected to the negative terminal of battery 40, and
22 that a variable frequency/duty pulse generator 60 is provided, instead of
23 the pulse generator 51 and pulse width modulator 52 of Fig. 1. Pulse
24 generator 60 takes its energy from the winding 10c and comprises a parallel
25 circuit of a diode 61 and a capacitor 62, connected to the lower end of the
26 auxiliary secondary winding 10c, and a resistor 63 connected between the
27 parallel diode-capacitor combination and the base of the switching
28 transistor 41. A transistor 64 is provided in the pulse generator 60 such that
29 its emitter and collector are connected to the base and emitter of switching
30 transistor 41, respectively, and its base is connected to the collector of ~ NE-545 ~108073 photo-transistor 54b. Across the feedback secondary winding 10c is 2 connected a series circuit of a capacitor 65 and a diode 66 which allows 3 current to flow from the upper end of winding 10c through capacitor 65 to 4 the lower end of the winding. The junction between capacitor 65 and diode s 66 is connected to the emitter of photo-transistor 54b.
6 The normal operation of the switching regulator of Fig. 2 is the 7 same as the previous embodiment. During a low input voltage condition, 8 the switch 42 is open in response to the low voltage indication signal from 9 low voltage detector 24, and the base of switching transistor 41 is supplied 10 with a small current that flows from battery 40 through resistor 59. This 11 triggers the transistor 41 into conduction, causing a current to be supplied 12 from battery 40 to the main secondary winding 1Ob. Because of the 13 inductive coupling, a voltage is induced in the feedback winding 1 Oc in 14 response to the current pulse in the main secondary winding 1Ob. The l S lower end of the winding 10c is driven to a potential higher than its upper 16 end and the diode 61 is biased forward to turn on the transistor 64. The 17 turn-on of transistor 64 causes the switching transistor 41 to turn off so that 18 the current from the battery 40 ceases to exist. Upon termination of the 19 current, the lower end of the winding 10c is driven to a potential lower than20 its upper end and the diode 61 is backward biased to allow transistor 64 to 21 turn off, while diode 66 is forward biased to store energy into capacitor 65.22 Capacitor 62, which stores energy during the on-state of transistor 64, now 23 discharges the stored energy to allow the transistor 64 to be rapidly turned 24 off, while capacitor 65 is developing a voltage that assists the transistor 64 to 2 S reduce the period of transition from the turn-on to the turn-off state.
2 6 Transistor 64 remains turned off, allowing the switching transistor 41 to turn 27 on again with the result that a subsequent current is produced in the main 28 winding 10b and a corresponding voltage is induced in the auxiliary winding 29 lOc. The above process is repeated and transistor 64 is turned on and off 3 0 as long as the low voltage condition prevails. The turn-off period of 2 1 0~073 transistor 64 as well as its on-off rate, and hence the frequency and duty 2 ratio of the pulse produced by the pulse generator 60 are determined by 3 the variable impedance of photo-transistor 54b that is connected between 4 the base of transistor 64 and the capacitor 65, so that the amount of AC
S energy supplied to the main secondary winding 10b is inversely 6 proportional to the DC output voltage developed across terminals 46, 47.
7 A further modification of the embodiment of Fig. 1 is shown in Fig.
8 3. According to this modification, a rechargeable battery 71 is used as a 9 backup power source in combination with the clock driven pulse width 10 control scheme of Fig. 1. As illustrated, the transformer 10 has an auxiliary11 secondary winding 10d which is used as a source for charging the battery 12 71 when the switching regulator is supplied with the rated AC voltage. A
13 rectifier 70 of voltage-doubler configuration is connected to the auxiliary 14 secondary winding 1 Od. Rectifier 70 is comprised by a capacitor 74 and a 1 S diode 75 connected in series across the winding 1 Od to develop a voltage in16 capacitor 74 when the lower end of winding 1 Od is driven to a positive 17 potential. Across the diode 75 is connected a series of a diode 76 and a 18 capacitor 77 to allow the energy stored on capacitor 74 to be discharged 19 through diode 76 into capacitor 77 when the upper end of winding 10d is 20 driven to a positive potential. The voltage developed in capacitor 77, which 21 iS twice as high as the voltage across capacitor 74. The voltages developed 22 in capacitors 74 and 77 are respectively applied to a low voltage detector 23 72 and a battery charger 73. When the mains AC voltage at the input 24 terminals 14, 15 is higher than the rated value, the voltage across capacitor25 74 is higher than a specified threshold, and no output is produced by the 2 6 low voltage detector 72 and the switch 42 remains closed. During this 27 normal operation, battery charger 73 is supplied with sufficient DC energy 28 from rectifier 70 to charge the battery 71 in preparation for possible power 29 failures. The low-voltage indication signal from the low voltage detector 72 30 is also applied to the battery charger 73 as a disabling signal to cause it to ~ 21 08073 stop its charging operation.
2 If the mains AC voltage becomes lower than the rated value, the 3 voltage across capacitor 74 becomes lower than the specified threshold, 4 and the low voltage detector 72 generates a low voltage indication signal to s open the switch 42, allowing the transistor 41 to respond to the output of 6 pulse width modulator 52 and successively feeding a current from battery 7 71 to the secondary winding 10b and the battery charger 73 ceases its 8 charging operation.
g The embodiment of Fig. 3 is modified as shown in Fig. 4, in which 10 the variable frequency/duty pulse generator 60 of Fig. 2 is used instead of 11 the clocked pulse width modulation circuitry of Fig. 3 by additionally 12 coupling the feedback secondary winding 1 Oc at one end to the 13 rechargeable battery 71 and further coupling it at opposite ends to the 14 variable frequency/duty pulse generator 60 in the same manner as in Fig. 2.
l S The operation of this embodiment is the same as of the self-oscillation of 16 Fig. 2 combined with the battery charging of Fig. 3.
17 A further modification of the embodiment of Fig. 3 is shown in Fig.
18 S in which the transformer 10 has a single secondary winding 10b. In this 19 embodiment, the transformer 10 is designed to deliver sufficient power to the battery charger 73. A rectifier 80 of voltage-doubler configuration is 21 connected across the secondary winding 10b and the clocked pulse width 22 modulation of Fig. 1 is employed. The rectifier 80 comprises a series of a 23 capacitor 81 and a diode 82 connected across the secondary winding 10b, 24 and a series of a capacitor 83 and a diode 84 connected in shunt with the diode 82. When the upper end of winding 10b is driven positive, the diode 26 82 is forward biased to cause a current to flow through capacitor 81 to the 27 lower end of winding 10b. When the latter is driven positive, the diode 84 is 28 forward biased, producing a current that flows through capacitor 83, diode 29 84 and capacitor 81 to the upper end of winding 1 Ob. A voltage twice as high as that developed in the winding 1 Ob is stored in capacitor 83. The . ~ 1 08073 battery charger 73 is connected in series to the negative power output line 2 of the rectifier 80. Since it is necessary to directly couple the positive output 3 line of the rectifier 80 to the secondary winding lOb, the battery charger 73 4 is positively grounded. The voltage across the capacitor 83 is applied to the S low voltage detector 72 as a representative of the AC input voltage.
6 The embodiment of Fig. 5 is modified as shown in Fig. 6 in which a 7 voltage stabilizer 98 is used, instead of the feedback circuit including the8 photo-coupler 54, to maintain the DC output voltage constant. Connected 9 to the secondary winding 10b is a rectifier 90 of voltage-doubler 10 configuration, which includes a series of diode 91 and capacitor 92 to 11 generate a first current in the winding lOb and a series of diode 93 and 12 capacitor 94 coupled across the diode 91 to generate a second, opposite 13 current in the winding lOb. A low voltage detector 95 is connected across 14 the capacitor 91 to operate a normally open power switch 99 for 15 connecting the outputs of voltage stabilizer 98 to the output terminals 46 16 and 47 when a low voltage condition is detected. A battery charger 96 is 17 powered by a voltage developed across the capacitor 94 to charge a 18 rechargeable battery 97 whose voltage is usually maintained at a level 19 higher than the rated value of the load circuit coupled to the output 20 terminals 46, 47. The voltage stabilizer 98 is connected to the battery 97 to21 produce a constant DC voltage. A rectifier 100 is connected to the 22 secondary winding lOb to supply a DC output voltage to the output 2 3 terminals 46, 47.
24 Under normal operating conditions, transistor 21 is turned on and off by pulse width modulator 23 in the same manner as described in the 26 previous embodiments, producing high frequency energy in the primary 27 winding lOa which is transferred to the secondary winding 10b and 2 8 converted by rectifier 100 into a DC voltage for delivery to the output 29 terminals 46, 47. The same high frequency energy is converted by rectifier 90 into DC energy, and a voltage twice as high as one developed across the winding lOb appears across the capacitor 94 and energizes the battery 2 charger 96. Rechargeable battery 97 is constantly charged in this way 3 during normal operating conditions in preparation for power failures. The 4 DC output voltage generated during normal operations is monitored by thephoto-coupler 53 and the amount of the high frequency energy input to the 6 primary winding lOa is controlled so that the DC output voltage is 7 maintained constant in the same manner as in the previous embodiments.
8 If power failure occurs, the low voltage detector 95 produces a low g voltage indication signal that closes the power switch 99 for coupling the stabilized DC voltage to the output terminals 46, 47. This low voltage 11 indication signal is also applied to the battery charger 96 as a disabling 12 signal to cause it to stop charging the battery 97.
6 The normal operation of the switching regulator of Fig. 2 is the 7 same as the previous embodiment. During a low input voltage condition, 8 the switch 42 is open in response to the low voltage indication signal from 9 low voltage detector 24, and the base of switching transistor 41 is supplied 10 with a small current that flows from battery 40 through resistor 59. This 11 triggers the transistor 41 into conduction, causing a current to be supplied 12 from battery 40 to the main secondary winding 1Ob. Because of the 13 inductive coupling, a voltage is induced in the feedback winding 1 Oc in 14 response to the current pulse in the main secondary winding 1Ob. The l S lower end of the winding 10c is driven to a potential higher than its upper 16 end and the diode 61 is biased forward to turn on the transistor 64. The 17 turn-on of transistor 64 causes the switching transistor 41 to turn off so that 18 the current from the battery 40 ceases to exist. Upon termination of the 19 current, the lower end of the winding 10c is driven to a potential lower than20 its upper end and the diode 61 is backward biased to allow transistor 64 to 21 turn off, while diode 66 is forward biased to store energy into capacitor 65.22 Capacitor 62, which stores energy during the on-state of transistor 64, now 23 discharges the stored energy to allow the transistor 64 to be rapidly turned 24 off, while capacitor 65 is developing a voltage that assists the transistor 64 to 2 S reduce the period of transition from the turn-on to the turn-off state.
2 6 Transistor 64 remains turned off, allowing the switching transistor 41 to turn 27 on again with the result that a subsequent current is produced in the main 28 winding 10b and a corresponding voltage is induced in the auxiliary winding 29 lOc. The above process is repeated and transistor 64 is turned on and off 3 0 as long as the low voltage condition prevails. The turn-off period of 2 1 0~073 transistor 64 as well as its on-off rate, and hence the frequency and duty 2 ratio of the pulse produced by the pulse generator 60 are determined by 3 the variable impedance of photo-transistor 54b that is connected between 4 the base of transistor 64 and the capacitor 65, so that the amount of AC
S energy supplied to the main secondary winding 10b is inversely 6 proportional to the DC output voltage developed across terminals 46, 47.
7 A further modification of the embodiment of Fig. 1 is shown in Fig.
8 3. According to this modification, a rechargeable battery 71 is used as a 9 backup power source in combination with the clock driven pulse width 10 control scheme of Fig. 1. As illustrated, the transformer 10 has an auxiliary11 secondary winding 10d which is used as a source for charging the battery 12 71 when the switching regulator is supplied with the rated AC voltage. A
13 rectifier 70 of voltage-doubler configuration is connected to the auxiliary 14 secondary winding 1 Od. Rectifier 70 is comprised by a capacitor 74 and a 1 S diode 75 connected in series across the winding 1 Od to develop a voltage in16 capacitor 74 when the lower end of winding 1 Od is driven to a positive 17 potential. Across the diode 75 is connected a series of a diode 76 and a 18 capacitor 77 to allow the energy stored on capacitor 74 to be discharged 19 through diode 76 into capacitor 77 when the upper end of winding 10d is 20 driven to a positive potential. The voltage developed in capacitor 77, which 21 iS twice as high as the voltage across capacitor 74. The voltages developed 22 in capacitors 74 and 77 are respectively applied to a low voltage detector 23 72 and a battery charger 73. When the mains AC voltage at the input 24 terminals 14, 15 is higher than the rated value, the voltage across capacitor25 74 is higher than a specified threshold, and no output is produced by the 2 6 low voltage detector 72 and the switch 42 remains closed. During this 27 normal operation, battery charger 73 is supplied with sufficient DC energy 28 from rectifier 70 to charge the battery 71 in preparation for possible power 29 failures. The low-voltage indication signal from the low voltage detector 72 30 is also applied to the battery charger 73 as a disabling signal to cause it to ~ 21 08073 stop its charging operation.
2 If the mains AC voltage becomes lower than the rated value, the 3 voltage across capacitor 74 becomes lower than the specified threshold, 4 and the low voltage detector 72 generates a low voltage indication signal to s open the switch 42, allowing the transistor 41 to respond to the output of 6 pulse width modulator 52 and successively feeding a current from battery 7 71 to the secondary winding 10b and the battery charger 73 ceases its 8 charging operation.
g The embodiment of Fig. 3 is modified as shown in Fig. 4, in which 10 the variable frequency/duty pulse generator 60 of Fig. 2 is used instead of 11 the clocked pulse width modulation circuitry of Fig. 3 by additionally 12 coupling the feedback secondary winding 1 Oc at one end to the 13 rechargeable battery 71 and further coupling it at opposite ends to the 14 variable frequency/duty pulse generator 60 in the same manner as in Fig. 2.
l S The operation of this embodiment is the same as of the self-oscillation of 16 Fig. 2 combined with the battery charging of Fig. 3.
17 A further modification of the embodiment of Fig. 3 is shown in Fig.
18 S in which the transformer 10 has a single secondary winding 10b. In this 19 embodiment, the transformer 10 is designed to deliver sufficient power to the battery charger 73. A rectifier 80 of voltage-doubler configuration is 21 connected across the secondary winding 10b and the clocked pulse width 22 modulation of Fig. 1 is employed. The rectifier 80 comprises a series of a 23 capacitor 81 and a diode 82 connected across the secondary winding 10b, 24 and a series of a capacitor 83 and a diode 84 connected in shunt with the diode 82. When the upper end of winding 10b is driven positive, the diode 26 82 is forward biased to cause a current to flow through capacitor 81 to the 27 lower end of winding 10b. When the latter is driven positive, the diode 84 is 28 forward biased, producing a current that flows through capacitor 83, diode 29 84 and capacitor 81 to the upper end of winding 1 Ob. A voltage twice as high as that developed in the winding 1 Ob is stored in capacitor 83. The . ~ 1 08073 battery charger 73 is connected in series to the negative power output line 2 of the rectifier 80. Since it is necessary to directly couple the positive output 3 line of the rectifier 80 to the secondary winding lOb, the battery charger 73 4 is positively grounded. The voltage across the capacitor 83 is applied to the S low voltage detector 72 as a representative of the AC input voltage.
6 The embodiment of Fig. 5 is modified as shown in Fig. 6 in which a 7 voltage stabilizer 98 is used, instead of the feedback circuit including the8 photo-coupler 54, to maintain the DC output voltage constant. Connected 9 to the secondary winding 10b is a rectifier 90 of voltage-doubler 10 configuration, which includes a series of diode 91 and capacitor 92 to 11 generate a first current in the winding lOb and a series of diode 93 and 12 capacitor 94 coupled across the diode 91 to generate a second, opposite 13 current in the winding lOb. A low voltage detector 95 is connected across 14 the capacitor 91 to operate a normally open power switch 99 for 15 connecting the outputs of voltage stabilizer 98 to the output terminals 46 16 and 47 when a low voltage condition is detected. A battery charger 96 is 17 powered by a voltage developed across the capacitor 94 to charge a 18 rechargeable battery 97 whose voltage is usually maintained at a level 19 higher than the rated value of the load circuit coupled to the output 20 terminals 46, 47. The voltage stabilizer 98 is connected to the battery 97 to21 produce a constant DC voltage. A rectifier 100 is connected to the 22 secondary winding lOb to supply a DC output voltage to the output 2 3 terminals 46, 47.
24 Under normal operating conditions, transistor 21 is turned on and off by pulse width modulator 23 in the same manner as described in the 26 previous embodiments, producing high frequency energy in the primary 27 winding lOa which is transferred to the secondary winding 10b and 2 8 converted by rectifier 100 into a DC voltage for delivery to the output 29 terminals 46, 47. The same high frequency energy is converted by rectifier 90 into DC energy, and a voltage twice as high as one developed across the winding lOb appears across the capacitor 94 and energizes the battery 2 charger 96. Rechargeable battery 97 is constantly charged in this way 3 during normal operating conditions in preparation for power failures. The 4 DC output voltage generated during normal operations is monitored by thephoto-coupler 53 and the amount of the high frequency energy input to the 6 primary winding lOa is controlled so that the DC output voltage is 7 maintained constant in the same manner as in the previous embodiments.
8 If power failure occurs, the low voltage detector 95 produces a low g voltage indication signal that closes the power switch 99 for coupling the stabilized DC voltage to the output terminals 46, 47. This low voltage 11 indication signal is also applied to the battery charger 96 as a disabling 12 signal to cause it to stop charging the battery 97.
Claims (16)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A switching regulator having an input circuit and an output circuit, comprising:
a single transformer having a primary winding connected in said input circuit for receiving direct-current energy and a secondary winding connected in said output circuit;
monitor means for monitoring direct-current energy in said output circuit;
a switching element connected in series with said primary winding;
high frequency pulse generator means energized by the direct-current energy in said input circuit for producing a high frequency pulse and causing said switching element to interrupt said direct-current energy supplied to said primary winding in response to the high frequency pulse, said pulse having a duty ratio inversely variable as a function of the direct-current energy monitored by said monitor means;
rectifier means connected in said output circuit for converting high frequency energy developed in said secondary winding into direct-current energy;
low voltage detector means for producing a low voltage indication signal when said direct-current energy in said input circuit falls below a specified value;
a battery; and means connected to said battery for deriving constant direct-current energy from said battery and coupling the constant direct-current energy to said output circuit in response to said low voltage indication signal.
a single transformer having a primary winding connected in said input circuit for receiving direct-current energy and a secondary winding connected in said output circuit;
monitor means for monitoring direct-current energy in said output circuit;
a switching element connected in series with said primary winding;
high frequency pulse generator means energized by the direct-current energy in said input circuit for producing a high frequency pulse and causing said switching element to interrupt said direct-current energy supplied to said primary winding in response to the high frequency pulse, said pulse having a duty ratio inversely variable as a function of the direct-current energy monitored by said monitor means;
rectifier means connected in said output circuit for converting high frequency energy developed in said secondary winding into direct-current energy;
low voltage detector means for producing a low voltage indication signal when said direct-current energy in said input circuit falls below a specified value;
a battery; and means connected to said battery for deriving constant direct-current energy from said battery and coupling the constant direct-current energy to said output circuit in response to said low voltage indication signal.
2. A switching regulator as claimed in claim 1, wherein said means for deriving constant direct-current energy comprises:
a second switching element connected in series with said battery across said secondary winding, and second high frequency pulse generator means energized by the direct-current energy in said output circuit for generating a high frequency pulse with a variable duty ratio and causing said second switching element to interrupt a current supplied from said battery in response to said pulse in the presence of said low voltage indication signal, said duty ratio being inversely proportional to the direct-current energy monitored by said monitor means.
a second switching element connected in series with said battery across said secondary winding, and second high frequency pulse generator means energized by the direct-current energy in said output circuit for generating a high frequency pulse with a variable duty ratio and causing said second switching element to interrupt a current supplied from said battery in response to said pulse in the presence of said low voltage indication signal, said duty ratio being inversely proportional to the direct-current energy monitored by said monitor means.
3. A switching regulator as claimed in claim 2, wherein the secondary winding is a main secondary winding, and said transformer has an auxiliary secondary winding and said battery is a rechargeable battery which is connected between said main secondary winding and said auxiliary secondary winding, further comprising:
second rectifier means connected to said auxiliary secondary winding for producing a direct-current energy; and a battery charger for receiving the direct-current energy from the second rectifier means and charging said rechargeable battery.
second rectifier means connected to said auxiliary secondary winding for producing a direct-current energy; and a battery charger for receiving the direct-current energy from the second rectifier means and charging said rechargeable battery.
4. A switching regulator as claimed in claim 2, wherein said battery is a rechargeable battery, further comprising:
second rectifier means connected to said secondary winding for producing a direct-current energy; and a battery charger for receiving the direct-current energy from the second rectifier means and charging said rechargeable battery.
second rectifier means connected to said secondary winding for producing a direct-current energy; and a battery charger for receiving the direct-current energy from the second rectifier means and charging said rechargeable battery.
5. A switching regulator as claimed in claim 1, wherein the secondary winding is a main secondary winding, and said transformer has an auxiliary secondary winding, and wherein said means for deriving constant direct-current energy comprises.
a second switching element connected in series with said battery across the main secondary winding; and second high frequency pulse generator means connected to said auxiliary secondary winding for generating a high frequency pulse with a variable duty ratio and causing said second switching element to interrupt a current supplied from said battery in response to said pulse in the presence of said low voltage indication signal, said duty ratio being inversely proportional to the direct-current energy monitored by said monitor means.
a second switching element connected in series with said battery across the main secondary winding; and second high frequency pulse generator means connected to said auxiliary secondary winding for generating a high frequency pulse with a variable duty ratio and causing said second switching element to interrupt a current supplied from said battery in response to said pulse in the presence of said low voltage indication signal, said duty ratio being inversely proportional to the direct-current energy monitored by said monitor means.
6. A switching regulator as claimed in claim 5, wherein said transformer has a second auxiliary secondary winding and said battery is a rechargeable battery which is connected between said main secondary winding and said second auxiliary secondary winding, further comprising:
second rectifier means connected to said second auxiliary secondary winding for producing direct-current energy; and a battery charger for receiving the direct-current energy from the second rectifier means and charging said rechargeable battery.
second rectifier means connected to said second auxiliary secondary winding for producing direct-current energy; and a battery charger for receiving the direct-current energy from the second rectifier means and charging said rechargeable battery.
7. A switching regulator as claimed in claim 1, wherein said battery is a rechargeable battery, and wherein said means for deriving constant direct-current energy comprises:
second rectifier means connected to said secondary winding for converting high frequency energy developed therein to direct-current energy;
a battery charger for receiving the direct-current energy from the second rectifier means and charging said rechargeable battery;
a voltage stabilizer connected to said rechargeable battery and producing a constant direct-current voltage; and means for applying said constant direct-current voltage to said output circuit in response to said low voltage indication signal.
second rectifier means connected to said secondary winding for converting high frequency energy developed therein to direct-current energy;
a battery charger for receiving the direct-current energy from the second rectifier means and charging said rechargeable battery;
a voltage stabilizer connected to said rechargeable battery and producing a constant direct-current voltage; and means for applying said constant direct-current voltage to said output circuit in response to said low voltage indication signal.
8. A switching regulator as claimed in any of claims 3, 4, 6 and 7, wherein said low voltage detector means 18 connected to said second rectifier means.
9. A switching regulator as claimed in claim 2 or 7, wherein said monitor means comprises:
a first photo-coupler having a light emitting diode and a photo-transistor; and a second photo-coupler having a light emitting diode and a photo-transistor, the light emitting diodes of the first and second photo-couplers being connected in series to said output circuit, and the photo-transistor of the first photo-coupler receiving direct-current energy from the input circuit and being connected to the first-mentioned high frequency pulse generator means as a variable impedance element, and the photo-transistor of the second photo-coupler receiving direct-current energy from the output circuit and being connected to the second high frequency pulse generator means as a variable impedance element.
a first photo-coupler having a light emitting diode and a photo-transistor; and a second photo-coupler having a light emitting diode and a photo-transistor, the light emitting diodes of the first and second photo-couplers being connected in series to said output circuit, and the photo-transistor of the first photo-coupler receiving direct-current energy from the input circuit and being connected to the first-mentioned high frequency pulse generator means as a variable impedance element, and the photo-transistor of the second photo-coupler receiving direct-current energy from the output circuit and being connected to the second high frequency pulse generator means as a variable impedance element.
10. A switching regulator as claimed in clalm 3, wherein the second rectifier means comprises:
a first rectifier circuit having a first capacitor and a first diode connected in series across said auxiliary secondary winding; and a second rectifier circuit having a second capacitor and a second diode connected in series across said first diode and applying a voltage developed in said second capacitor to said battery charger.
a first rectifier circuit having a first capacitor and a first diode connected in series across said auxiliary secondary winding; and a second rectifier circuit having a second capacitor and a second diode connected in series across said first diode and applying a voltage developed in said second capacitor to said battery charger.
11. A switching regulator as claimed in claim 4, wherein the second rectifier means comprises:
a first rectifier circuit having a first capacitor and a first diode connected in series across said secondary winding; and a second rectifier circuit having a second capacitor and a second diode connected in series across said first diode and applying a voltage developed in said second capacitor to said battery charger.
a first rectifier circuit having a first capacitor and a first diode connected in series across said secondary winding; and a second rectifier circuit having a second capacitor and a second diode connected in series across said first diode and applying a voltage developed in said second capacitor to said battery charger.
12. A switching regulator as claimed in claim 6, wherein the second rectifier means comprises:
a first rectifier circuit having a first capacitor and a first diode connected in series across said second auxiliary secondary winding; and a second rectifier circuit having a second capacitor and a second diode connected in series across said first diode and applying a voltage developed in said second capacitor to said battery charger.
a first rectifier circuit having a first capacitor and a first diode connected in series across said second auxiliary secondary winding; and a second rectifier circuit having a second capacitor and a second diode connected in series across said first diode and applying a voltage developed in said second capacitor to said battery charger.
13. A switching regulator as claimed in claim 7, wherein the second rectifier means comprises:
a first rectifier circuit having a first capacitor and a first diode connected in series across said secondary winding; and a second rectifier circuit having a second capacitor and a second diode connected in series across said first diode and applying a voltage developed in said second capacitor to said battery charger.
a first rectifier circuit having a first capacitor and a first diode connected in series across said secondary winding; and a second rectifier circuit having a second capacitor and a second diode connected in series across said first diode and applying a voltage developed in said second capacitor to said battery charger.
14. A switching regulator having an input circuit for receiving direct-current energy and an output circuit, comprising:
a single transformer having a primary winding connected in said input circuit for receiving direct-current energy and a secondary winding connected in said output circuit;
monitor means for monitoring direct-current energy in said output circuit;
a first switching element connected in said input circuit in series with said primary winding;
first high frequency pulse generator means energized by the direct-current energy of said input circuit for producing a first high frequency pulse and causing said first switching element to interrupt said direct-current energy of said input circuit in response to the first high frequency pulse, said first high frequency pulse having a duty ratio inversely variable as a function of the direct-current energy monitored by said monitor means;
first rectifier means connected in said output circuit for converting high frequency energy produced in said secondary winding into said direct-current energy of said output circuit.
low voltage detector means for producing a low voltage indication signal when said direct-current energy of said input circuit falls below a specified value;
a rechargeable battery;
second rectifier means connected to said secondary winding for converting high frequency energy produced therein to direct-current energy;
a battery charge for receiving direct-current energy from the second rectifier means and charging said rechargeable battery;
a stabilizer connected to said rechargeable battery for producing a constant direct-current energy; and means for applying said constant direct-current energy to said output circuit in response to said low voltage indication signal.
a single transformer having a primary winding connected in said input circuit for receiving direct-current energy and a secondary winding connected in said output circuit;
monitor means for monitoring direct-current energy in said output circuit;
a first switching element connected in said input circuit in series with said primary winding;
first high frequency pulse generator means energized by the direct-current energy of said input circuit for producing a first high frequency pulse and causing said first switching element to interrupt said direct-current energy of said input circuit in response to the first high frequency pulse, said first high frequency pulse having a duty ratio inversely variable as a function of the direct-current energy monitored by said monitor means;
first rectifier means connected in said output circuit for converting high frequency energy produced in said secondary winding into said direct-current energy of said output circuit.
low voltage detector means for producing a low voltage indication signal when said direct-current energy of said input circuit falls below a specified value;
a rechargeable battery;
second rectifier means connected to said secondary winding for converting high frequency energy produced therein to direct-current energy;
a battery charge for receiving direct-current energy from the second rectifier means and charging said rechargeable battery;
a stabilizer connected to said rechargeable battery for producing a constant direct-current energy; and means for applying said constant direct-current energy to said output circuit in response to said low voltage indication signal.
15. A switching regulator as claimed in claim 14, wherein said low voltage detector means is connected to said second rectifier means.
16. A switching regulator as claimed in claim 14, wherein said monitor means comprises:
a first photo-coupler having a light emitting diode and a photo-transistor, a second photo-coupler having a light emitting diode and a photo-transistor, the light emitting diodes of the first and second photo-couplers being connected in series to said output circuit, and the photo-transistor of the first photo-coupler receiving direct-current energy from the input circuit and being connected to the first high frequency pulse generator means as a variable impedance element, and the photo-transistor of the second photo-coupler receiving direct-current energy from the output circuit and being connected to the second high frequency pulse generator means as a variable impedance element.
a first photo-coupler having a light emitting diode and a photo-transistor, a second photo-coupler having a light emitting diode and a photo-transistor, the light emitting diodes of the first and second photo-couplers being connected in series to said output circuit, and the photo-transistor of the first photo-coupler receiving direct-current energy from the input circuit and being connected to the first high frequency pulse generator means as a variable impedance element, and the photo-transistor of the second photo-coupler receiving direct-current energy from the output circuit and being connected to the second high frequency pulse generator means as a variable impedance element.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP27216792 | 1992-10-12 | ||
| JP4-272167 | 1992-10-12 | ||
| JP5-203792 | 1993-08-18 | ||
| JP5203792A JP2638436B2 (en) | 1992-10-12 | 1993-08-18 | Switching regulator |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2108073A1 CA2108073A1 (en) | 1994-04-13 |
| CA2108073C true CA2108073C (en) | 1998-11-03 |
Family
ID=26514123
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002108073A Expired - Fee Related CA2108073C (en) | 1992-10-12 | 1993-10-08 | Single transformer switching regulator |
Country Status (6)
| Country | Link |
|---|---|
| US (1) | US5414611A (en) |
| EP (1) | EP0592977B1 (en) |
| JP (1) | JP2638436B2 (en) |
| AU (1) | AU667960B2 (en) |
| CA (1) | CA2108073C (en) |
| DE (1) | DE69312206T2 (en) |
Families Citing this family (22)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP3287086B2 (en) * | 1993-12-17 | 2002-05-27 | 株式会社ニプロン | Switching regulator |
| DE4435747A1 (en) * | 1994-10-06 | 1996-04-11 | Bosch Telecom | Circuit arrangement for a DC voltage converter |
| US5757627A (en) * | 1996-05-01 | 1998-05-26 | Compaq Computer Corporation | Isolated power conversion with master controller in secondary |
| US5862044A (en) * | 1996-12-02 | 1999-01-19 | Yokogawa Electric Corporation | Switching power supply unit |
| JP3286673B2 (en) * | 1997-01-24 | 2002-05-27 | 浩 坂本 | Converter circuit for charger |
| JP2956681B2 (en) * | 1998-02-27 | 1999-10-04 | 富士電機株式会社 | Switching operation circuit of switching power supply |
| US6462971B1 (en) * | 1999-09-24 | 2002-10-08 | Power Integrations, Inc. | Method and apparatus providing a multi-function terminal for a power supply controller |
| US6108217A (en) * | 1999-10-19 | 2000-08-22 | Ivi Checkmate Ltd. | Backup power circuit |
| KR100419393B1 (en) * | 1999-12-09 | 2004-02-21 | 산켄덴키 가부시키가이샤 | Dc-dc converter |
| JP4618468B2 (en) * | 2000-04-07 | 2011-01-26 | ソニー株式会社 | Power supply |
| US6577512B2 (en) * | 2001-05-25 | 2003-06-10 | Koninklijke Philips Electronics N.V. | Power supply for LEDs |
| US6775164B2 (en) * | 2002-03-14 | 2004-08-10 | Tyco Electronics Corporation | Three-terminal, low voltage pulse width modulation controller IC |
| US6865094B2 (en) | 2002-05-14 | 2005-03-08 | International Business Machines Corporation | Circuit for AC adapter to reduce power drawn from an AC power source |
| KR100736364B1 (en) * | 2005-05-03 | 2007-07-06 | 삼성전자주식회사 | Image sensor capable of amending ADC ramp slope and method thereof |
| US8137670B2 (en) * | 2005-09-29 | 2012-03-20 | Medimmune, Llc | Method of identifying membrane IgE specific antibodies and use thereof for targeting IgE producing precursor cells |
| US8953343B2 (en) * | 2007-04-30 | 2015-02-10 | Samsung Electronics Co., Ltd. | Power supply apparatus having multiple outputs |
| JP5268615B2 (en) * | 2008-12-15 | 2013-08-21 | キヤノン株式会社 | Power supply device and image forming apparatus |
| US8576522B2 (en) | 2010-10-28 | 2013-11-05 | Hamilton Sundstrand Corporation | Shunt regulator at excitation output of generator control unit for overvoltage protection |
| KR20150054222A (en) * | 2013-11-11 | 2015-05-20 | 삼성전자주식회사 | A device and method fot supplying the power |
| JP6394094B2 (en) * | 2014-06-18 | 2018-09-26 | 富士通株式会社 | Power supply circuit and power factor correction circuit |
| DE102014012664A1 (en) * | 2014-08-22 | 2016-02-25 | Eaton Protection Systems Ip Gmbh & Co. Kg | Supply voltage detection device and method for detecting a supply voltage |
| CN112543532B (en) * | 2020-12-15 | 2023-09-26 | 上海晶丰明源半导体股份有限公司 | Dimming control circuit and device thereof |
Family Cites Families (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5886615A (en) * | 1981-11-19 | 1983-05-24 | Ricoh Co Ltd | Power source circuit |
| DE3736372C1 (en) * | 1987-10-27 | 1989-01-05 | Nixdorf Computer Ag | Switching power supply |
| JP2686135B2 (en) * | 1989-03-28 | 1997-12-08 | 松下電工株式会社 | Constant current power supply circuit |
| JPH02266866A (en) * | 1989-04-06 | 1990-10-31 | Nec Corp | Switching regulator |
| US4996638A (en) * | 1990-02-15 | 1991-02-26 | Northern Telecom Limited | Method of feedback regulating a flyback power converter |
| KR920003586Y1 (en) * | 1990-04-14 | 1992-05-30 | 주식회사 금성사 | Magnetron driving circuit of mwo |
| US5297014A (en) * | 1991-01-09 | 1994-03-22 | Canon Kabushiki Kaisha | Switching DC power supply apparatus |
| JPH04120118U (en) * | 1991-04-03 | 1992-10-27 | スタンレー電気株式会社 | switching regulator |
| US5301095A (en) * | 1991-10-01 | 1994-04-05 | Origin Electric Company, Limited | High power factor AC/DC converter |
-
1993
- 1993-08-18 JP JP5203792A patent/JP2638436B2/en not_active Expired - Lifetime
- 1993-10-08 US US08/134,270 patent/US5414611A/en not_active Expired - Fee Related
- 1993-10-08 CA CA002108073A patent/CA2108073C/en not_active Expired - Fee Related
- 1993-10-11 DE DE69312206T patent/DE69312206T2/en not_active Expired - Fee Related
- 1993-10-11 EP EP93116407A patent/EP0592977B1/en not_active Expired - Lifetime
- 1993-10-12 AU AU48994/93A patent/AU667960B2/en not_active Ceased
Also Published As
| Publication number | Publication date |
|---|---|
| US5414611A (en) | 1995-05-09 |
| AU4899493A (en) | 1994-04-28 |
| DE69312206T2 (en) | 1998-03-05 |
| JP2638436B2 (en) | 1997-08-06 |
| CA2108073A1 (en) | 1994-04-13 |
| EP0592977B1 (en) | 1997-07-16 |
| AU667960B2 (en) | 1996-04-18 |
| EP0592977A2 (en) | 1994-04-20 |
| JPH06233529A (en) | 1994-08-19 |
| DE69312206D1 (en) | 1997-08-21 |
| EP0592977A3 (en) | 1996-02-07 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| MKLA | Lapsed |